Railroads are under increasing pressure to reduce emissions and to increase fuel efficiency. One of several responses to these forces has been the development of hybrid locomotives. Donnelly has disclosed the use of a battery-dominant hybrid locomotive in U.S. Pat. No. 6,308,639 which is incorporated herein by reference. Hybrid locomotives can reduce emissions and fuel consumption in rail operations such as yard switching but they are less effective for medium haul freight or commuter trains.
In U.S. patent application Ser. No. 11/200,88 filed Aug. 19, 2005 entitled “Locomotive Power Train Architecture”, Donnelly et al. have further disclosed a general electrical architecture for locomotives based on plurality of power sources, fuel and drive train combinations. The power sources may be any combination of engines, fuel cells, energy storage and regenerative braking. This application is also incorporated herein by reference.
Multi-engine locomotives are not new and a number of configurations have been built over the years. Examples are the Baldwin locomotives built in the 1940s and, more recently, a dual engine locomotive built by the French Railway Company, VFLI. In U.S. patent application Ser. No. 11/201,267 filed Aug. 9, 2005 entitled “Multiple Engine Locomotive Configuration”, Donnelly et al. have disclosed a means of packaging engine modules on a multi-engine locomotive that optimizes the power density of the locomotive power plants while reducing emissions and fuel consumption.
There remains a need for a versatile control strategy for multi-prime power source vehicles such as locomotives with an appropriate control strategy that can reduce emissions and fuel consumption over the entire spectrum of railroad applications and does not have to rely on energy storage systems and regenerative braking to gain these advantages.